1. Field of the Invention
The subject invention relates to hinged needle shields that can be rotated into shielding relationship with a needle cannula for preventing accidental sticks.
2. Description of the Prior Art
A needle cannula is an elongate metal tube having a proximal end, a distal end and a lumen extending between the ends. The proximal end of the needle cannula may be securely engaged in the distal end of a medical implement, such as a hypodermic syringe. Alternatively, the proximal end of the prior art needle cannula may be securely engaged in a needle hub, which in turn is removably engageable with a medical implement. The distal end of the prior art needle cannula typically is beveled to define a sharp point.
Needle cannulas often are used with needle shields to prevent accidental contact with the pointed distal end of the needle cannula. One type of prior art needle shield includes a rigid U-shaped channel having a proximal end, a distal end and a length slightly greater than the length of the needle cannula. The proximal end of the U-shaped channel is hingedly mounted to the needle hub or to some other structure near the proximal end of the needle cannula. Thus the prior art hinged needle shield can be rotated between a first position where the needle cannula is safely enclosed within the hinged needle shield and a second position where the needle cannula is exposed for use.
Hinged needle shields have several very desirable attributes. For example, the prior art hinged needle shield does not require a specially manufactured hypodermic syringe. Thus, the hub of a needle assembly having a hinged needle shield thereon can be connected to a hypodermic syringe in the conventional manner, without affecting the size and feel of the hypodermic syringe. Additionally, the prior art hinged needle shield enables the needle cannula to be easily accessed or shielded. In particular, both shielding and unshielding are carried out by application of digital forces at locations spaced from the distal tip of the needle cannula and in directions transverse to the longitudinal axis of the needle cannula.
One drawback of the prior art hinged needle shield relates to the potential for visual or physical interference when the needle shield is hingedly moved into its open position to permit use of the needle cannula. In particular, a doctor, nurse or other medical technician may want a specified orientation of the bevel on the distal end of the needle cannula to achieve a precise positioning of the point formed by the bevel. Additionally, a specified rotational orientation of the needle cannula may help to gauge the depth of insertion. The hinged needle shield could be fixed on the needle cannula at a rotational orientation that visually obstructs the medical technician's view of the injection site. At other times, the needle shield could contact the patient and thereby prevent the medical technician from having the needle cannula aligned at a small acute angle to the patient.
Some medical procedures require administration of a specified dose of a drug. In these situations, the medical technician may have to closely inspect the volume measuring indicia on the syringe barrel during the injection. Once again, the hinged needle shield could visually obscure the volume measuring indicia.